One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,5)(6,8)(9,10,13,16)(11,14,17,18)(12,15,20,22)(19,21,23,24)(25,26)(27,33)(28,31)(29,37)(30,32)(34,38)(35,39)(36,40)(2,5)(6,7)(9,10)(11,14)(12,15)(13,16)(17,18)(19,21)(20,22)(23,24)(25,27,30,28)(26,31,32,33)(29,35,38,36)(34,39,37,40)(1,2)(3,6)(4,5)(7,8)(11,17)(12,20)(14,18)(15,22)(26,32)(29,38)(31,33)(35,36) involution — undirected(1,3,4,8)(2,6,5,7)(9,10)(11,18)(12,15)(13,16)(14,17)(19,24)(20,22)(21,23)(25,28,30,27)(26,33,32,31)(29,36,38,35)(34,40,37,39)(9,11,13,17)(10,14,16,18)(12,19,20,23)(15,21,22,24)(25,26)(27,33)(28,31)(29,34)(30,32)(35,40)(36,39)(37,38)(9,12)(10,15)(11,19)(13,20)(14,21)(16,22)(17,23)(18,24)(25,29,30,38)(26,34,32,37)(27,35,28,36)(31,39,33,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.